EP1255268A1 - Microrelay circuit for off and on switching of alternating currents - Google Patents

Abstract

The circuit has a first micro relay switch (1), a second (2) in parallel with the first and in series with a diode (10) and a measurement device (5) for detecting at least the polarity of the current in the parallel circuit. During a switch-off process the circuit receives a switch-off signal, detects the current polarity, opens the first switch if the polarity corresponds to diode conduction and opens the second switch if the diode is blocking.

Description

Technical field

The invention relates to one designed for AC applications Circuit used to switch off or on currents or voltages is used. This AC circuit contains at least two microrelay switches.

State of the art

To switch off or on currents or voltages in the Low voltage range essentially conventional relays or contactors used. These are usually conventional (macroscopic) Switches that are operated electromagnetically.

Because of the considerable size and the great weight of such relays or In recent times, contactors have increasingly become microrelays as switches for them or other switching tasks examined. Microrelays are with Methods of semiconductor technology and / or microstructure technology produced microscopic Switches that are often, but not necessarily, on silicon wafers and can be realized using silicon technology. they promise a variety of advantages, depending on the application, more or less can be in the foreground. So they are naturally much smaller and lighter than conventional relays and also faster in switching speed. They can also handle smaller powers, currents or voltages operate.

However, problems exist in particular with regard to the maximum permissible Voltage and current loads during switching or during switching operations itself. This is due to the small geometric dimensions and consequently relatively small opening distances, contact areas and contact forces.

Presentation of the invention

The invention is based on the technical problem of an improved AC circuit with microrelay for switching off or switching on alternating currents or alternating voltages.

According to the invention, an AC circuit is provided for this on the one hand with a first microrelay switch, one to the first microrelay switch second microrelay switch in parallel with the first diode, one at least the polarity of the current through the parallel connection from the first Microrelay switch on the one hand and the series connection from the second microrelay switch and the first diode measuring device, which circuit is designed for a switch-off process: a switch-off signal to receive, then to detect the polarity of the current at one of the Forward direction of the first diode corresponding current polarity to the first microrelay switch to open and then at one of the reverse direction of the first diode corresponding current polarity to open the second microrelay switch, and an AC circuit with a first micro relay switch, one to the first micro relay switch in parallel and in series with the first diode second microrelay switch, at least the polarity of the parallel circuit from the first micro relay switch on the one hand and the series connection from the second microrelay switch and the first diode Voltage measuring device, which circuit is designed to when switching on: to receive a switch-on signal, then the polarity to detect the voltage at a direction corresponding to the blocking direction of the first diode Voltage polarity to close the second micro relay switch and then at a voltage polarity corresponding to the forward direction of the first diode to close the first micro relay switch.

Preferred embodiments are specified in the dependent claims.

The invention therefore relates to a parallel connection, at least in one branch a first microrelay switch is included and at least in its other branch a second microrelay switch and a first one connected in series Diode is included. Furthermore, a measuring device should measure the polarity of the current detect the voltage across the entire parallel circuit at least if a signal instructing a shift is received. One on shutdowns designed circuit according to the invention then opens first the first microrelay switch, and only when the detected one Polarity of the forward direction of the first diode corresponds. If now the first When the micro relay switch is opened, the current flows through the second micro relay switch containing circuit branch, so that the switching off of the first Micro relay switch is largely relieved. Then instead of the system voltage drops at the first micro relay switch essentially the sum of the forward voltage the first diode and any other significant voltages in the still conductive circuit branch. This can result in reverse polarity the second micro relay switch can be opened, which is preferably in the next Half-period or at a later time if desired with a suitable one Polarity can be done. This switch-off process is practically load-free because now the first diode blocks and thus also the essential part of the voltage drop wearing.

With another controller, the same parallel connection can be used from the two Microrelay switches and the diode a favorable switch-on process can be realized. For this purpose, the polarity of the at least after receiving the switch-on signal Voltage is detected by the second micro relay switch when the first diode is off close. Then the first microrelay switch can operate with reversed polarity getting closed. Because of when the second micro relay switch is closed blocking diode, the second micro relay switch is practically voltage and closed when de-energized. When the first micro relay switch closes again conducts the circuit branch containing the first diode and the second micro relay switch, so that the first micro relay switch largely voltage and is closed without power. With regard to the individual switching operations So it is about the time reversal of the previously described switch-off process.

The two switching concepts can of course also be implemented simultaneously by one and the same AC circuit both the described shutdown process as well as perform the switch-on process described above the same micro relay switches and the same diode are used. It can the same measuring device can also be used. In particular, it should be noted that a measuring device that detects the voltage polarity is located above it Polarity ultimately also the polarity of the current flowing through the circuit can capture. Conversely, a measuring resistor can of course also be used an actual current measurement will determine the voltage polarity.

Assuming an ordinary AC application, for example with household voltage in the phase or with a three-phase application in one Phase, the current and voltage curves are periodic and correspond the time periods of a certain polarity each half period. In the worst conceivable case the switching signal occurs at the beginning of an "inappropriate" Half period, so that for at least a short half period to one for the first partial switching operation must be serviced at a suitable time and inclusive the reversed polarity required for the second partial switching operation the overall switching process thus takes up at least a short period. In many applications, this is not a problem because of the shutdown processes do not have to be done particularly quickly anyway.

However, the circuits according to the invention can be improved further, by adding another circuit branch to the parallel connection already described which is a series connection of a second diode and a third Includes micro relay switch. The first and second diodes are antiparallel to each other. Therefore, the circuit after receiving the Switching signal first a switching process in a momentarily blocking Start the diode branch circuit branch and then reverse Polarity the micro relay switch in the circuit branch with the other of the two Let the diodes switch. The first micro relay switch can be used at any time are switched to by one of the two diodes due to polarity and the circuit state of the second and third micro relay switches Current can flow (including the current and voltage zeros). The first Microrelay switch can therefore be switched off first, especially when switched off or in the same period in which the first of the two diode-serial Micro relay switch is turned off. Conversely, when switching on the first microrelay switch can be turned on as the very last one or, for example in the same half-period as the last of the two switched on diode serial micro relay switch.

In any case, the described improved embodiments of the circuits according to the invention, the entire switching operations even in the case of an unfavorable situation Time of the switching signal depending on the speed of operation of the Circuit can be completed in just over a half period.

The circuits according to the invention can measure current or voltage perform in the various preferred variants. The easiest and because of this simplicity also preferred case is detection of only the polarity, where necessary, a detection threshold can be introduced, so not At the end of a half period, a polarity is still determined, which, however, for the the amount of time required for the individual switching processes no longer lasts. In any case, this embodiment is based on a real amplitude or phase detection waived and only the minimum necessary information to choose from the appropriate circuit branches detected.

In another preferred possibility, however, the amplitude or the phase of current or voltage detected and used in such a way that the current or voltage-loaded switch-on and switch-off processes, if possible, in the Close to the zeros. During the switch-on and switch-off processes can namely the micro-relay switch due to the non-vanishing forward voltage the diodes are still slightly loaded. Single switching operations near the zeros can further reduce this burden. In addition, the individual switching operations could be close to one and the same Run zero, so that none between the individual switching operations high current or voltage values occur more. In particular, this can then be of interest if the loading of the diodes with those in use occurring current or voltage values is problematic. The diodes then namely the full current or full voltage wear only around the zeros. In this context, of course also be provided by the diodes in conductive normal operation Protect protective resistors from excessive current values, so that then the voltage drops across these protective resistors the switching operations for the Micro relay switches in the parallel branches are subjected to greater loads. It can be of particular interest, the switching operations in the range of small amplitudes to lay.

To improve the current or voltage strength of the invention Circuits can also be provided in this application with the term "Microrelay switches" do not refer to switches made from a single microrelay to build up but from a series connection or parallel connection of several Micro-relay. In the same way, they can simply be referred to as "diodes" Components actually a parallel or series connection of a plurality of Diodes correspond to the current carrying capacity and / or dielectric strength improve.

It has already been said that microrelays are often large technological Have parallels to classic semiconductor components and in particular often consist at least partially of semiconductor materials, preferably silicon. Therefore, the diodes can be placed in corresponding parts of the micro relay switch be integrated, that is, be applied approximately on the same chip as one of the mentioned Series or parallel connection of several individual microrelays. They can also be integrated in a component of a single microrelay. In particular can the series or parallel connections of the microrelay and Diodes may also be interlaced with one another, so that they are actually series or parallel connections of respective sets of diodes and microrelays.

In addition, the aforementioned measuring device can be implemented in an integrated manner his.

Finally, it is also possible to multiply the circuit according to the invention interconnect, parallel connections and series connections of the invention Circuit are advantageous. With parallel connections of microrelays the simultaneity of the switch-on and switch-off processes is a fundamental one Problem. If only one of the microrelays opens a little later or closes, it comes with a disproportionate share of the current or voltage values loaded. However, if the circuit according to the invention several times in parallel or is connected in series, it is no longer a matter of precise synchronicity essential. The invention then ensures that the individual microrelays are better protected.

If it is not tolerable in a particular application, that with the Circuits according to the invention only with a certain time delay a switch-off signal can be reacted to, for example because of a very large fault current or short-circuit current occurs that must be interrupted immediately, one can Circuit according to the invention also combined with an additional fuse be that triggers in such cases. For less critical shutdowns then the circuit according to the invention can be used, as well as conventionally For example, load switches can be combined with short-circuit fuses. The backup can advantageously also by the in the invention Circuit provided anyway measuring device can be controlled.

Various exemplary embodiments of the invention are explained below to illustrate more specifically. Features disclosed here can also be found in others be essential to the invention as the combinations shown. It will be on it pointed out that the above and the following overall disclosure of the Registration is also to be understood with regard to corresponding working procedures.

Brief description of the figures

Figur 1 ein schematisches Schaltdiagramm für eine erfindungsgemäße Schaltung zum Ausschalten eines Stroms;

Figur 2 eine vereinfachte Variante zu Figur 1 als zweites Ausführungsbeispiel;

Figur 3 eine verbesserte Variante zu Figur 2 als drittes Ausführungsbeispiel;

Figur 4 ein schematisches Schaltdiagramm eines verbesserten Details aus Figur 1 als viertes Ausführungsbeispiel;

Figur 5 eine schematische Darstellung einer konkreten Ausführungsform eines Schaltungsastes aus einer der Figuren 1-3;

Figur 6 eine schematische Darstellung einer Variante zu Figur 5; und

Figur 7 eine schematische Darstellung einer Variante zu den Figuren 5 und 6.

In detail shows:

1 shows a schematic circuit diagram for a circuit according to the invention for switching off a current;

Figure 2 shows a simplified variant of Figure 1 as a second embodiment;

Figure 3 shows an improved variant of Figure 2 as a third embodiment;

FIG. 4 shows a schematic circuit diagram of an improved detail from FIG. 1 as a fourth exemplary embodiment;

Figure 5 is a schematic representation of a specific embodiment of a circuit branch from one of Figures 1-3;

Figure 6 is a schematic representation of a variant of Figure 5; and

FIG. 7 shows a schematic illustration of a variant of FIGS. 5 and 6.

Ways of Carrying Out the Invention

Figures 1 and 2 show a schematic representation of the two explained Variants of the invention with three or two parallel branches. 1 denotes the first microrelay switch, 2 the second microrelay switch and 3 the third Micro-relay switches. 10 denotes the first diode, 9 the second diode. With 5 is denotes the measuring device, which here is also the control for the micro relay switch 1-3 contains, as indicated by the dashed switching lines 6, 7 and 8. The arrow labeled I indicates the current direction to a certain one Time.

If you imagine that the micro relay switches 1, 2 and 3 are all closed are and the drawn current I flows, and further imagines that, as indicated with the signal line 13, a switch-off signal in the measuring device 5 integrated control reached, it is clear that in both variants (Figure 1 and Figure 2) the first micro relay switch 1 can be opened. The Current I can continue through the forward polarity of the first diode 10 and flow second microrelay switch 2, so that the first microrelay switch 1, apart from the forward voltage of the first diode, is opened without load. After the polarity of the current I changes, the second microrelay switch 2 be opened, which is because of the blocking polarity of the first diode 10th is also practically load-free. Because the first diode has a reverse polarity resistance so high that it conducts almost no current and practically all of it voltage applied to the circuit drops at the first diode 10. at the variant in FIG. 1, however, requires that the third micro relay switch 3 is already open. To open this also practically unencumbered , it is preferably in the same half-period as the first micro relay switch 1 open, i.e. easiest practically at the same time. This opening process does not apply to the second variant from FIG. 2. However, this has the Disadvantage that with a polarity reversed to the current direction shown the first microrelay switch 1 cannot be opened without a load, but initially a polarity change must be awaited. In this case the second variant from FIG. 2 not only the switch-off signal on the line 13 chronologically following half-period, but also part of the next but one Half period.

In order to be able to decide depending on the current polarity whether at the first Variant simultaneous with the first micro relay switch 1, the second 2 or the third 3 is opened and then the third 3 or the second 2 after a polarity change is opened, or to be able to decide in the second variant, whether the first micro relay switch 1 immediately or only after a polarity change can be opened and the second micro relay switch 2 in the next or can be opened in the next but one half period, requires the in the circuit 5 included control so information about the current polarity in these two exemplary embodiments via a sign detection limiting current detection indicated in the figures with 4 takes place.

In contrast, FIG. 3 shows an otherwise the second exemplary embodiment FIG. 2 corresponding improved third variant, in which the measuring device 5 additionally via lines 11 and 12 the polarity of the voltage on the parallel circuit from the two microrelay switches 1 and 2 and the first diode 10 taps. A similar addition is also easy for the first embodiment from Figure 1.

In this third exemplary embodiment, the polarity of the voltage can be applied the parallel connection is determined even when the micro relay switches 1 and 2 are open become.

With this third exemplary embodiment, an improved switch-on process can also be performed realize. To do this, imagine that in a situation where the voltage polarity designated U is present, which is the forward direction of the corresponds to the first diode 10, via line 13 a switch-on signal in the controller is entered in the circuit 5. The controller then uses the measuring device and the lines 11 and 12 that the first diode 10 in Forward direction is polarized and waits for the next polarity change. Then it closes the second microrelay switch 2, which is due to the isolation by the first diode 10 is practically unloaded. After another polarity change the first micro relay switch 1 can also be switched on without load, because it is then bridged by the parallel circuit branch. It is clear that at a three-branch variant as in Figure 1 (but with voltage measurement) in the 3, the third microrelay switch 3 is immediately switched on could be, and after the next polarity change then the two remaining micro relay switches 1 and 2. Otherwise, the explanations apply the switch-off processes in the examples from FIGS. 1 and 2 analogously.

If you only look at switch-on processes or the voltage drop at the Parallel connection, even in the conductive state, is sufficient for detection here the current polarity detection 4 is superfluous because of the voltage polarity the current polarity also results in the conductive state of the circuit.

The switch-on processes according to the invention are of particular interest, if the device powered by the affected circuit at power up shows undesirably high starting currents. This mainly affects technical devices core-enforced coils, such as transformers, up to core saturation have relatively low impedance. Through the switch-on process according to the invention the current increases with the start of the relevant half-wave, if the too the diode in series becomes conductive when the microrelay switch is switched on, gently. During the physical switch-on, it can be blocked the diode practically no starting currents flow.

Figure 4 shows a variant of Figure 1 with a fourth embodiment. There the micro relay switches 1, 2 and 3 are each implemented by parallel connections individual microrelays, designated 1 ', 2' and 3 '. As by the invention Switch the effectively switchable currents (using the diodes 9 and 10) are greatly increased, it also makes sense to increase the current carrying capacity in the conductive Increase condition. This can be done in a simple manner through the parallel connections shown 1 ', 2', 3 'happen. For the current carrying capacity in the conductive state it does not depend on the timing mentioned above between switching operations. The parallel connections are otherwise on a common silicon chip 11 integrated. The following working examples show that the diodes 9 and 10 can also be taken into account. The Measuring device 5 with its measuring lines is omitted in FIG. 4, so that FIG 4 shows only a section of the previous figures 1-4.

FIG. 5 shows a microrelay switch 2 ″ as a specific embodiment for (example) the second microrelay switch from FIGS. 1-3. This microrelay switch 2 "is built on a silicon chip 11" which contains a first diode 10 ". This diode 10 "is conventional per se, by dopant diffusion in the silicon wafer 11 "and subsequent contacting produced diode P-contact 14 is connected to the fixed contact piece 15 of the microrelay switch 2 " is.

The fixed contact piece 15 is opposite a movable contact piece 16 the one vertically (with respect to the position in Figure 5) elastically movable spring tongue heard, which can be actuated by an electrostatic capacitor 17, to bring the contact pieces 15 and 16 into and out of contact with each other.

The technological details of the microrelay switch 2 "shown are apart from the combination with the diode conventional and are so far not explained in detail. Incidentally, this could also be a parallel connection act in the manner of the micro-relay switch 2 'from Figure 4, the individual Microrelays are staggered in the direction orthogonal to the drawing plane.

FIG. 6 shows a further technological variant of a micro relay switch, which is designated here with 2 '' '. In this case, the line of sight of the figure is vertical aligned to the wafer, not shown, on which the designated 18 Base is firmly attached. On two narrow long elastically deformable Carriers 19 is a movable contact piece 20 held by a electrostatic capacitor 21 with a toothed comb-like structure substantially horizontally (with reference to FIG. 6). This horizontal mobility results from the elasticity compared to the vertical (with reference to FIG. 6) considerably higher transverse elasticity of the narrow beams 19.

The movable contact piece 20 thus bridges two fixed contact pieces 22 and 23 on the right side of Figure 6. The fixed contact piece 23 is again followed by a diode 10 ″ ″, which otherwise corresponds to the diode 10 ″ from FIG. 5, however, is shown in FIG. 6 in a perspective rotated by 90 °.

The details of the embodiment of the microrelay 2 ″ illustrated in FIG. 6 reference is made to European parallel application 018110322.6 of the same Applicant.

FIG. 7 shows a last embodiment variant for the microrelay, which is shown here with 2 "" is designated. This embodiment is based on the German patent application 100 40 867.2 dated 21.08.2000, which contains the technical details of the Microrelay 2 "" disclosed. Here again a diode 10 "" is added, which is technical corresponds to the diode 10 "from FIG. 5 and the diode 10 '" from FIG.

The micro relay switch 2 "" is characterized by one on its two outermost Ends fixed flexible movable contact piece 24, which in its lower Dashed position and solid in its upper position (switched off) is shown. It has an electrically conductive layer in its left area 25, which is connected to the diode 10 "". The conductive layer can with a Contact 26 are connected, for which purpose the movable contact piece 24 from an activation mechanism that is vertically movable with respect to FIG 27 is actuated with an electrostatic capacitor 28. The upper Position of the movable contact piece 24 is stable by itself while the lower layer is only maintained by the activation mechanism 27 can be.

The activation mechanism 27 essentially has a vertically extending, built in a silicon framework pattern and tapering Thorn on, which is movable parallel to the substrate (vertical in Figure 7, so viewing direction substratorthogonal). To do this, it is connected to one above the electrostatic capacitor schematically indicated elastic structure suspended. The electrostatic The capacitor has a comb-like toothed structure. The microrelay 2 "" from the figure Like the previous micro relay 2 '' 'from FIG. 6, 7 is characterized by a relative large stroke between open and closed state and thus relatively large Dielectric strength in the open state. Furthermore, the contact forces cheap when closed. For details, refer to the referenced Registration referred.

LIST OF REFERENCE NUMBERS

1, 1 ', 2, 2', 2 '', 2 '' ', 2' '', 3, 3 '

Micro relay switch

4

Current polarity detection

5

Measuring device with integrated control

6, 7, 8

Control lines for micro relay switches

9

second diode

10

first diode

11

Silicon chip with three parallel connections from microrelays

12

Voltage polarity detection

13

Signal line for switching signal

14

Contact (between diode and fixed contact piece)

15

fixed contact piece

16

movable contact piece

17

electrostatic drive capacitor

18

fixed base for movable contact piece

19

elastic straps

20

movable contact piece

21

electrostatic drive capacitor

22, 23

fixed contact pieces

24

movable contact piece (flexible bendable)

25

conductive layer on it

26

fixed contact piece

27

activation mechanism

28

electrostatic drive capacitor

Claims (17)

AC circuit with
a first micro relay switch (1, 1 '),
a second microrelay switch (2-2 "") parallel to the first microrelay switch (1, 1 ') and in series with a first diode (10),
a measuring device (5) which detects at least the polarity of the current (I) due to the parallel connection of the first micro-relay switch (1, 1 ') on the one hand and the series connection of the second micro-relay switch (2-2 "") and the first diode (10) on the other hand .
which circuit is designed to do so when switching off: to receive a switch-off signal (13), then detect the polarity of the current (I) to open the first microrelay switch (1, 1 ') at a current polarity corresponding to the forward direction of the first diode (10) and then open the second microrelay switch (2-2 "") at a current polarity corresponding to the blocking direction of the first diode (10). AC circuit according to claim 1
with a series connection of a second diode (9) which is parallel to the first microrelay switch (1, 1 ') on the one hand and to the series circuit comprising the second microrelay switch (2-2 "") and the first diode (10) on the other hand, and which in reverse Sense of direction as the first diode (10) is connected, and a third microrelay switch (3, 3 '),
the circuit is designed to: after receiving the switch-off signal (13) to open the microrelay switch (2-2 "", 3, 3 ') which is in series with a momentarily blocking diode (9, 10), with reversed current polarity, open the microrelay switch (3, 3 ', 2-2 "") which is in series with the other diode (10, 9) then blocking and to open the first microrelay switch (1, 1 ') when current flows through one of the diodes (9, 10). AC circuit, also according to claim 1 or 2, with
a first micro relay switch (1, 1 '),
a second microrelay switch (2-2 "") parallel to the first microrelay switch (1, 1 ') and in series with a first diode (10),
at least the polarity of the measuring device (5) sensing the parallel circuit comprising the first micro-relay switch (1, 1 ') and the series circuit comprising the second micro-relay switch (2-2 "") and the first diode (10),
which circuit is designed for this when switching on: to receive a switch-on signal (13), then detect the polarity of the voltage (U) to close the second microrelay switch (2-2 "") if the voltage polarity corresponds to the blocking direction of the first diode (10) and then close the first microrelay switch (1, 1 ') at a voltage polarity corresponding to the forward direction of the first diode (10). AC circuit according to claim 3
with a series connection of a second diode (9) which is parallel to the first microrelay switch (1, 1 ') on the one hand and to the series circuit comprising the second microrelay switch (2-2 "") and the first diode (10) on the other hand Sense of direction as the first diode (10) is connected, and a third microrelay switch (3, 3 '),
the circuit is designed to: after receiving the switch-on signal (13) to close the microrelay switch (2-2 "", 3, 3 ') which is in series with the currently blocking diode (9, 10), with reverse voltage polarity, close the microrelay switch (3, 3 ', 2-2 "") which is in series with the other diode (10, 9) which is then blocking and to close the first microrelay switch (1, 1 ') when current flows through one of the diodes (9, 10). AC circuit according to one of the preceding claims, in which the measuring device (5) is designed to detect only the polarity. AC circuit according to one of claims 1-4, which is designed for this is current or voltage-loaded switching on or off of the Microrelay switch (1, 1 ', 2-2 "", 3, 3') by detecting the amplitude or the phase of the current (I) or the voltage (U) of the measuring device (5) in close to the zeros. AC circuit according to claim 1, also in connection with a further of the preceding claims, in which the measuring device (5) is designed, the current (I) through the parallel connection via the at the parallel connection to detect the applied voltage (U). AC circuit according to one of the preceding claims, in which at least one of the microrelay switches (1, 1 ', 2-2 "", 3, 3') has a parallel connection from individual microrelays. AC circuit according to one of the preceding claims, in which at least one of the microrelay switches (1, 1 ', 2-2 "", 3, 3') has a series connection from individual microrelays. AC circuit according to one of the preceding claims, in which at least one of the diodes (9, 10) is a parallel connection of individual ones Has diodes. AC circuit according to one of the preceding claims, in which at least one of the diodes (9, 10) is a series connection of individual ones Has diodes. AC circuit according to one of the preceding claims, in which at least one of the diodes (9, 10) with at least part of the in series lying micro-relay switch (2-2 "", 3, 3 ') is integrated. AC circuit according to one of the preceding claims, in which the measuring device (5) with the microrelay switches (1, 1 ', 2-2 "", 3, 3') integrated is. AC circuit, which is a parallel connected plurality of AC circuits each having one of the preceding claims correspond. AC circuit, which is a series-connected plurality of AC circuits each having one of the preceding claims correspond. AC circuit with an AC circuit according to claim 1, also in connection with another of the preceding claims, and an additional safety device to protect against very large Overflowing. AC circuit according to claim 16, wherein the measuring device also serves to control the safety device.

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